The manufacture and use of synthetic laundry detergents containing mixtures of nonionic and anionic surfactants have been documented in the patent literature.
Liquid surfactant compositions are well known in the field of laundry detergents and, whether for domestic or industrial applications, practically all of the available formulations are solutions of one or more surface active materials (surfactants) in water, together with an organic solvent if necessary. Such formulations usually contain only about 10 wt% to 45 wt% active matter.
There are certain problems involved in the use of relatively dilute formulations such as the difficulty and high cost of transporting the formulation from its point of manufacture to its point of sale. Since most of the formulation's bulk is water, it would be very advantageous from the standpoint of shipping costs to prepare more concentrated formulations.
By providing good detergency and foamability, alcohol ethoxysulfates are finding increasing use in household laundry powders and liquids as part of mixed active surfactant systems. However, a drawback to the use of alcohol ethoxysulfates in formulations is their strong gel forming tendencies as they are diluted into formulations having concentrations greater than 30%. Gel formation can be reduced by incorporating approximately 14% ethanol into 60% active matter solutions of alcohol ethoxysulfates. This relatively high active matter solution lowers shipping costs, but the presence of ethanol in alcohol ethoxysulfate solutions prevents their use in spray-dried or dry-blended laundry powders where the flammability and combustibility of ethanol are a significant processing hazard. In addition, excessive water prohibits the formation of a free-flowing powder when surfactant concentrates are blended with water-soluble detergent powder particles.
It is therefore an object of this invention to prepare surface active compositions comprising a blend of alcohol ethoxylates and alcohol ethoxysulfates with less than about 15% water and substantially free of any organic solvent. In the surfactant compositions of the present invention, an anionic surfactant, alcohol ethoxysulfate, is blended with a nonionic surfactant, alcohol ethoxylate, where each of these surfactant types act as mutual hydrotropes, thereby permitting liquid concentrates containing active matter levels of at least about 85%. It is a further object of this invention to provide concentrates which are clear, single-phase pourable liquids rather than gels at relatively low temperatures such as, for example, about 50.degree. C. or less.